The Equilibrium between Cerebrospinal Fluid and Blood Plasma

There are few data in the literature on the distribution of sodium between serum and cerebrospinal fluid. Mestrezat (1) determined the concentration of individual inorganic elements on a mixture of cerebrospinal fluid from twenty normal individuals and obtained a value of 322 mg. per 100 cc. for sodium. Pincus and Kramer (2) and Weston and Howard (3) have published short series of determinationsmade on samples of blood and spinal fluid taken at the same time. Pincus and Kramer state that the sodium concentration of spinal fluid is essentially the same as that of plasma although in nine out of eleven cases they found the same relationship that we consistently found, namely, slightly higher values for sodium in cerebrospinal fluid. Their figures in eleven instances average 331 mg. per 100 cc. for serum and 344 mg. per 100 cc. for cerebrospinal fluid. Weston and Howard in a series of twenty-seven cases of manic-depressive insanity obtained an average value-of 331 mg. per 100 cc. for both serum and cerebrospinal fluid, with a range of 297 to 343 mg. per 100 cc. in serum and 303 to 346 mg. per 100 cc. in cerebrospinal fluid. Leipold (4), quoted by Walter (5), gives values of 257 to 331 mg. of sodium per 100 cc. for spinal fluid and found the sodium value in the serum equal to that in the spinal fluid. Depisch and Richter-Quittner (6) have studied the inorganic elements in serum and cerebrospinal fluid. They have reported such extraordinary values, especially for calcium, as to cast serious doubt on the accuracy of the determinations reported.